JP5117775B2 - Pipe fitting mounting method and pipe joint structure for branch pipe - Google Patents

Description

  The present invention relates to a pipe joint mounting method for connecting a branch pipe to a pipe, and a pipe joint for a branch pipe. More specifically, the present invention relates to a pipe joint mounting method suitable for connecting a branch pipe to an existing main pipe such as a gas conduit and a water and sewage pipe, and a pipe joint for a branch pipe.

When connecting a branch pipe to a pipe (main pipe) mainly buried in the ground, such as a gas pipe or a water and sewage pipe, for example, a hole for communicating with the main pipe is opened in the main pipe and the end of the branch pipe is connected. There is also a method in which the portion is directly welded and fixed to the outer peripheral surface of the main pipe. However, with this method of welding and fixing the branch pipe to the main pipe, it takes time for welding work, and if the inner surface of the main pipe to be connected is lined, the lining may be heated and damaged. is there.
Therefore, as a method for connecting the branch pipe to the main pipe without fixing by welding, a technique using a pipe joint disposed between the branch pipe and the main pipe as described below has been proposed.

  2. Description of the Related Art Conventionally, there has been proposed a technique related to a pipe joint for branch pipe connection having a structure in which a main pipe is sandwiched between a joint receiver and a support member inserted into the main pipe and attached to the main pipe (see, for example, Patent Document 1). ). A pipe joint for branch pipe connection described in Patent Document 1 is a joint that is inserted into a main pipe from an oval or elliptical branch hole formed in the main pipe and is opposed to an inner peripheral surface around the branch hole of the main pipe. The joint receiver is fixed to the inner peripheral surface of the main pipe by fixing the receiver and the support member opposed to the outer peripheral surface around the branch hole with a screw and pressing the pressing bolt attached to the support member against the outer peripheral surface of the main pipe. And a pipe joint in which a joint body is screwed into a screw hole penetrating the joint receiver.

Utility Model Registration No. 2556296

  However, when the branch pipe connection pipe joint for connecting the branch pipe described in Patent Document 1 is attached to the main pipe, as described in Patent Document 1, an oval shape is provided for the main pipe. Or it is necessary to make an elliptical branch hole beforehand. However, it is not easy to form an oval or elliptical branch hole in the main pipe at the site, which is very laborious.

  This invention is made | formed in view of the said situation, The objective is to provide the pipe joint attachment method for attaching a branch pipe to a pipe | tube with work efficiency, and the pipe joint structure for branch pipes.

Means and effects for solving the problems

  The pipe joint attachment method according to the present invention relates to a pipe joint attachment method for connecting a branch pipe to a pipe. And the pipe joint attachment method which concerns on this invention has the following some features, in order to achieve the said objective. That is, the pipe joint mounting method of the present invention comprises the following features alone or in combination.

The first feature of the pipe joint mounting method according to the present invention for achieving the above object is that a pipe joint for a branch pipe having a joint body having a flange and a pressing plate attached to the joint body is formed on the pipe. a pipe joint mounting method of mounting the circular hole, recess forming step of two recesses for partially enlarged the hole formed in the pipe at a position facing each other on the peripheral of said hole And a flange insertion step of inserting the flange into the pipe through the two recesses formed in the hole, and the holding plate on the joint body in which the flange is inserted into the pipe. A pressing plate attaching step for penetrating, a pipe fastening step for clamping the wall surface of the tube by the pressing plate attached to the joint main body, and the flange portion inserted into the pipe, and tightening It is that you are.

According to this configuration, the flange part of the joint body is inserted into the pipe from the recess that can be easily formed in the hole of the pipe, and the wall surface of the pipe is sandwiched and tightened by the inserted hook part and the holding plate to be larger than the hole diameter. A pipe joint for a branch pipe having a flange part of a size can be securely fixed to the pipe, and the flange part can be firmly adhered to the inner surface of the pipe. That is, even if, for example, a circular hole is formed on the pipe, it is possible to attach the branch pipe joint to the pipe efficiently and reliably by using the concave portion. Even when pressure is applied, the branch pipe joint does not come out. And high airtightness and watertightness between a collar part and a pipe inner surface are ensured. Thereby, even if the fluid flows in the pipe at a high pressure, the fluid does not leak from the hole formed in the pipe. Moreover, it becomes possible to make the recessed part dimension per piece small, and the sealing performance between a pipe | tube and a coupling main body improves.

The second feature of the pipe joint fitting method according to the present invention, the concave portion is a small-diameter arcuate der Rukoto than the diameter of said hole.

When in this configuration, the recess of the circular arc is easily formed, the working efficiency is further improved by using a tool such as easy general drill obtain.

  The third feature of the pipe joint mounting method according to the present invention is that the joint body has a cylindrical portion, the pressing plate has an annular shape, and the outer peripheral surface of the cylindrical portion and the pressing plate Threaded portions are respectively formed on the inner peripheral surface of each of the two, and the pressing plate mounting step is a step of mounting the pressing plate to the joint body by screwing the pressing plate into the cylindrical portion, and the pipe tightening A process is a process of clamping the wall surface of the said pipe | tube with the said collar part and the said press plate by screwing the said press plate attached to the said coupling main body further into the said cylindrical part.

  According to this configuration, by screwing the presser plate into the cylindrical part, it is possible to connect the presser plate and the joint body and to clamp the tube wall surface between the flange part and the presser plate of the joint body. In other words, the screw portions formed on the outer peripheral surface of the cylindrical portion and the inner peripheral surface of the pressing plate can be used in the pressing plate attaching step and the pipe tightening step, and the working efficiency is further improved.

  Moreover, the 4th characteristic in the pipe joint attachment method which concerns on this invention is attaching the said pipe joint for branch pipes to the said pipe | tube by which the lining layer was formed in the internal peripheral surface. According to this configuration, even in a pipe having a lining layer, the fluid flowing through the pipe does not enter the gap between the pipe inner peripheral surface and the lining layer, and the fluid leaks from the hole formed in the pipe. There is nothing.

  The branch pipe joint structure according to the present invention also relates to a branch pipe joint structure for connecting a branch pipe to a pipe. And the pipe joint structure for branch pipes concerning this invention has the following some features in order to achieve the said objective. That is, the pipe joint structure for a branch pipe according to the present invention includes the following features alone or in combination as appropriate.

A first feature of a pipe joint structure for a branch pipe according to the present invention for achieving the above object is a pipe joint structure for a branch pipe that is attached to a circular hole formed in the pipe, the joint body having a flange portion; , and a pressing plate attached to the joint body, the bore of the tube, the recess to expand part the hole is cross two in a position opposite to the forming on the peripheral of the hole, two of the Passing the recess and inserting the flange into the tube, and clamping the wall of the tube between the inserted flange and the pressing plate penetrating the joint body.

According to this configuration, the flange part of the joint body is inserted into the pipe from the recess that can be easily formed in the hole of the pipe, and the wall surface of the pipe is sandwiched and tightened by the inserted hook part and the holding plate to be larger than the hole diameter. A pipe joint for a branch pipe having a flange part of a size can be securely fixed to the pipe, and the flange part can be firmly adhered to the inner surface of the pipe. That is, even if, for example, a circular hole is formed on the pipe, it is possible to attach the branch pipe joint to the pipe efficiently and reliably by using the concave portion. Even when pressure is applied, the branch pipe joint does not come out. And high airtightness and watertightness between a collar part and a pipe inner surface are ensured. Thereby, even if the fluid flows in the pipe at a high pressure, the fluid does not leak from the hole formed in the pipe. Moreover, it becomes possible to make the recessed part dimension per piece small, and the sealing performance between a pipe | tube and a coupling main body improves.

The second feature of the branch pipe fitting structure according to the present invention, the recess is that it is a small arcuate than the diameter of said hole.

When in this configuration, the recess of the circular arc is easily formed, the working efficiency is further improved by using a tool such as easy general drill obtain.

  The third feature of the pipe joint structure for a branch pipe according to the present invention is that the joint body has a cylindrical portion, the pressing plate has an annular shape, and the outer peripheral surface of the cylindrical portion and the pressing member Threaded portions are respectively formed on the inner peripheral surface of the plate, the retaining plate is attached to the joint body by screwing the retaining plate into the tubular portion, and the branching tube is threaded into the tubular portion by screwing the branch pipe into the tubular portion. A pipe is attached to the joint body.

  According to this configuration, the screw portion formed on the outer peripheral surface of the cylindrical portion can be used for both attachment of the pressing plate and the joint main body and connection between the joint main body and the branch pipe, and the working efficiency is further improved.

  Moreover, the 4th characteristic in the pipe joint structure for branch pipes which concerns on this invention is provided with the packing with which it mounts | wears between the said collar part and the said pipe internal peripheral surface. According to this structure, the sealing performance between the pipe and the joint body is improved.

  Moreover, the 5th characteristic in the pipe joint structure for branch pipes which concerns on this invention is that the lining layer is formed in the internal peripheral surface of the said pipe | tube. According to this configuration, the fluid flowing through the pipe does not enter the gap between the inner peripheral surface of the pipe and the lining layer, and the fluid does not leak from the hole formed in the pipe.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments for carrying out the invention will be described with reference to the drawings. The pipe joint mounting method and the pipe joint structure for a branch pipe according to the present invention are techniques suitable for connecting a branch pipe to a pipe on which an internal pressure acts, such as a gas pipe, a water supply pipe, and an agricultural water pipe. However, the present invention is not limited to pipes for these uses, and is a technique applicable to various pipes such as steel pipes and cast iron pipes for other uses. Further, the tube to be mounting the branch pipe fittings, also I mains (main pipe) der, may be branched pipe (branch pipe).

<First Embodiment>
FIG. 1 is a plan view showing a branch pipe fitting 1 according to a first embodiment of the present invention attached to a hole 50 formed in a main pipe 100. FIG. 2 is a cross-sectional view taken along the line AA of the branch pipe fitting 1 shown in FIG. In FIG. 1, the description of some members of the pipe joint 1 for a branch pipe is omitted in order to avoid complication of lines. On the inner surface of the main pipe 100, a lining layer such as a thermoplastic resin pipe, a fiber reinforced thermoplastic resin pipe, or a pipe formed by impregnating and curing a thermoplastic resin or a thermosetting resin on a fiber is formed.

  As shown in FIG. 1 and FIG. 2, the branch pipe fitting 1 of this embodiment is a branch pipe fitting 1 attached to a hole 50 formed in the main pipe 100, and includes a joint body 11 and a joint body 11. The presser plate 12 that is inserted, the external reinforcing plate 14 that is inserted into the joint main body 11 and is in contact with the outer peripheral surface 100 b of the main pipe 100, the flange portion 11 a of the joint main body 11 that is inserted into the joint main body 11, and the main pipe 100. The packings 15 and 17 and the internal reinforcing plate 16 mounted between the inner peripheral surface 100a, the spacer ring 18 disposed in the gap between the joint body 11 and the hole 50, and the holding plate 12 are screwed. A plurality of bolts 13 are provided.

  The joint main body 11 includes a cylindrical portion 11b and a flange portion 11a formed at one end of the cylindrical portion 11b. On the outer peripheral surface of the cylindrical portion 11b, a screw portion is formed from the other end of the cylindrical portion 11b facing the flange portion 11a toward the flange portion 11a. The flange portion 11 a is bent so as to be along the inner peripheral surface 100 a of the main pipe 100 and is in a form of surface contact with the inner peripheral surface 100 a of the main pipe 100. The pressing plate 12 is an annular flat plate material, and a screw portion is formed on the inner peripheral surface thereof. In addition, six screw holes for screwing the bolts 13 are formed in the presser plate 12 along the outer peripheral direction thereof. The holding plate 12 is attached to the joint body 11 by screwing the holding plate 12 into the threaded portion formed on the outer peripheral surface of the cylindrical portion 11b, and the branch pipe 101 connected to the main pipe 100 is connected to the threaded portion of the cylindrical portion 11b. The branch pipe 101 is attached to the joint body 11 by being screwed into the joint body 11. That is, the threaded portion formed on the outer peripheral surface of the cylindrical portion 11 b can be used for attachment of the holding plate 12 and the joint body 11 and connection of the joint body 11 and the branch pipe 101.

  A circular hole 50 is formed in the main pipe 100, and the hole 50 is arranged on the circumference of the hole 50 so that arcuate recesses 30 whose diameters are partially expanded outward are opposed to each other. Two are formed along. The outer diameter D of the flange 11a of the joint body 11 is smaller than the width L of the hole 50 at the portion expanded by the recess 30 but larger than the diameter of the hole 50, and the joint body 11 is pulled straight out of the hole 50. Is in a state that cannot be.

  The external reinforcing plate 14 is an annular plate material that is bent so as to follow the curved surface of the outer peripheral surface 100b of the main pipe 100 and is in surface contact with the outer peripheral surface 100b of the main pipe 100. The external reinforcing plate 14 is a member that reinforces the wall surface of the main pipe 100 to which the pipe joint is attached while causing the pressing force of the bolt 13 to act on the outer peripheral surface 100b of the main pipe 100 as evenly as possible.

  The packing 15, the internal reinforcing plate 16, and the packing 17 are arranged in this order so as to overlap from the inner peripheral surface 100a of the main pipe 100 toward the flange portion 11a. The packings 15 and 17 are plate-like rubber packings, and the outer periphery is formed in a rectangular shape and the inner periphery is formed in a circular shape. The materials and shapes of the packings 15 and 17 are not limited to these, and any of resin, metal, O-ring, ring, and the like may be used. Similarly, the internal reinforcing plate 16 has a plate shape, the outer periphery is formed in a rectangular shape, and the inner periphery is formed in a circular shape. Further, the internal reinforcing plate 16 is bent so as to be along the inner peripheral surface 100 a of the main pipe 100 and is in surface contact with the inner peripheral surface 100 a of the main pipe 100, and the packing 15, the inner surface of the main pipe 100, and the packing 17. It is a member for making the space | gap part 11a closely_contact | adhere. The widths W of the packings 15, 17 and the internal reinforcing plate 16 are shorter than the width L of the hole 50 enlarged by the recess 30, and the long side W ′ is sufficiently longer than the width L.

  The spacer ring 18 is an annular member loosely fitted into the tubular portion 11 b of the joint body 11, and is bent so as to follow the circumferential direction of the main pipe 100. The spacer ring 18 is a member for positioning the joint body 11 so as not to move in the direction along the wall surface of the main pipe 100 inside the hole 50. The material of the joint body 11, the pressing plate 12, the external reinforcing plate 14, the internal reinforcing plate 16, the spacer ring 18, and the bolt 13 is, for example, carbon steel or stainless steel.

  The bolt 13 is screwed into the holding plate 12 fixed by screwing into the cylindrical portion 11 b, and the outer peripheral surface 100 b of the main pipe 100 is pressed through the external reinforcing plate 14 at the end of the bolt 13. By pressing the outer peripheral surface 100 b with the end of the bolt 13, the wall surface of the main pipe 100 is clamped by the holding plate 12 and the flange portion 11 a, and thereby the branch pipe fitting 1 is formed on the main pipe 100. It is firmly attached to the hole 50.

  Next, the method for attaching the branch pipe fitting 1 to the main pipe 100 will be described in detail. FIG. 3 is a plan view showing the hole 50 formed in the main pipe 100. 4 is a cross-sectional view taken along the line CC in FIG. 3 showing a state in which the flange portion 11a of the joint body 11 is inserted into the hole 50 formed in the main pipe 100. FIG. FIG. 5 is a perspective view showing a state in which the flange portion 11 a of the joint body 11 is inserted into the hole 50 formed in the main pipe 100. FIG. 6 is a perspective view showing a state in which the internal reinforcing plate 16 is inserted into the hole 50 formed in the main pipe 100.

  As shown in FIG. 3, first, a circular hole 50 is formed at a position where the main pipe 100 is to be branched. The shape of the hole 50 is not limited to a circular shape. Next, two arc-shaped recesses 30 for partially expanding the holes 50 formed in the main pipe 100 are formed at positions facing the holes 50 (recess forming step). Here, in the technique described in Patent Document 1 described above, it is necessary to previously open an elliptical or elliptical branch hole that takes time and labor for processing the main pipe 100. On the other hand, according to the present invention, if a circular hole 50 that can be easily formed is provided in the main pipe, the branch pipe fitting 1 can be attached to the main pipe 100 as described later. That is, by using the recess formed by the recess forming step, the branch pipe fitting 1 can be attached to the main pipe 100 with high work efficiency, and as a result, the branch pipe 101 can be attached to the main pipe 100 with high work efficiency. It can be done. In addition, if the width L of the hole 50 of the part enlarged by the recessed part 30 is larger than the outer diameter D of the collar part 11a of the coupling main body 11, since the collar part 11a can be inserted in the main pipe 100, the recessed part 30 is 1 Only one may be formed. By forming two recesses 30 as in the present embodiment, the size of each recess can be reduced, and the sealing performance between the main pipe 100 and the joint body 11 is improved. Moreover, the circular arc-shaped recessed part 30 can be easily formed using tools, such as an easily available general drill, and work efficiency further improves.

  Next, the collar part 11a is inserted into the main pipe 100 using the recess 30 formed in the hole 50 (a collar part insertion process). In the flange insertion step, as shown in FIGS. 4 and 5, the flange 11 a is inserted into the hole 50 formed in the main pipe 100 while being appropriately inclined so that the flange 11 a passes through the recess 30. Go. The packings 15 and 17 and the internal reinforcing plate 16 are inserted into the main pipe 100 while being appropriately tilted from the side edge of the width W, and are loosely fitted into the cylindrical portion 11b inside the main pipe 100. At this time, if the joint body 11 can be fished with a string or the like, the joint body 11 can be temporarily dropped into the main pipe 100, and the packing 15 and the like can be easily loosely fitted into the tubular portion 11b. For example, the state in which the internal reinforcing plate 16 is inserted into the hole 50 formed in the main pipe 100 is shown in FIG. 6 (the air fishing means is not shown). The dimensions of the recess 30 are appropriately determined in consideration of the thickness of the flange portion 11a, the packings 15 and 17, and the internal reinforcing plate 16, the diameter of the hole 50, the outer diameter of the cylindrical portion 11b, and the like.

  Next, as shown in FIG. 2, the spacer ring 18 is inserted into the tubular portion 11 b of the joint body 11 and is disposed in the gap between the hole 50 of the main pipe 100 and the outer peripheral surface of the tubular portion 11 b. The external reinforcing plate 14 is inserted into the cylindrical portion 11 b and brought into contact with the outer peripheral surface 100 b of the main pipe 100. Thereafter, the presser plate 12 is inserted through the joint body 11 in which the flange portion 11a is inserted into the main pipe 100 (presser plate attaching step). In the presser plate attaching step, the presser plate 12 is screwed into the tubular portion 11b so that the presser plate 12 penetrates the joint body 11.

  Next, the wall surface of the main pipe 100 is sandwiched and tightened by the pressing plate 12 attached to the joint body 11 and the flange portion 11a inserted into the main pipe 100 (pipe fastening process). In the pipe tightening step, the bolt 13 is screwed into the holding plate 12 attached to the joint body 11, and the outer peripheral surface 100 b of the main pipe 100 is pressed through the external reinforcing plate 14 at the end of the bolt 13. By pressing the outer peripheral surface 100b with the end portion of the bolt 13, the wall surface of the main pipe 100 is clamped by the pressing plate 12 and the flange portion 11a. The branch pipe fitting 1 is firmly attached to the hole 50 formed in the main pipe 100 by sandwiching and tightening the wall surface of the main pipe 100 with the holding plate 12 and the flange portion 11a, and the packings 15 and 17 are sufficiently provided. Compressed, airtightness and watertightness between the joint body 11 and the main pipe 100 are ensured. Thereafter, the branch pipe 101 is screwed into the cylindrical portion 11 b to attach the branch pipe 101 to the joint body 11 and connect to the main pipe 100 via the branch pipe fitting 1.

  A branch pipe fitting 1 of this embodiment was attached to a hole formed in a φ150 steel pipe (main pipe) and an internal water pressure test was conducted. As a result, even if a water pressure of 3 MPa was applied for 5 minutes, the pipe fitting 1 for a branch pipe As a result, water leakage did not occur from the mounting part of the water, and sufficient applicability to water pipes and agricultural water pipes could be confirmed.

Second Embodiment
FIG. 7 is a view showing a branch pipe fitting 2 according to a second embodiment of the present invention. FIG. 7A is a cross-sectional view corresponding to FIG. 2 of the pipe joint 2 for a branch pipe, and FIG. 7B shows a pressing plate 12 ′ and an external reinforcing plate 14 as viewed from the E direction of FIG. It is a figure of '. In the description of the branch pipe joint 2, the same members as those in the branch pipe joint 1 of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown to Fig.7 (a), cylindrical part 11'b of coupling main body 11 'was formed toward the collar part 11a from the edge part of cylindrical part 11'b of the side facing the collar part 11a. The threaded portion is formed longer than the cylindrical portion 11b of the branch pipe fitting 1 to the side closer to the flange portion 11a. Further, unlike the pressing plate 12 of the branch pipe fitting 1, the pressing plate 12 ′ is not formed with a screw hole for screwing a bolt. Therefore, the branch pipe fitting 2 does not include a bolt. Further, as shown in FIG. 7 (b), the surface of the external reinforcing plate 14 ′ where the pressing plate 12 ′ and the external reinforcing plate 14 ′ are in contact with each other so that the external reinforcing plate 14 ′ is in surface contact with the pressing plate 12 ′. It is formed flat. The surface of the external reinforcing plate 14 ′ is not necessarily flat and may be a curved surface along the outer peripheral surface 100 b of the main pipe 100. That is, the external reinforcing plate 14 ′ may be formed by bending a plate material having a substantially constant thickness like the external reinforcing plate 14.

  Here, in the pipe tightening step when the pipe joint 2 for branch pipes is attached to the main pipe 100, the holding plate 12 ′ attached to the joint body 11 ′ is further screwed into the tubular portion 11′b of the joint body 11 ′. Thus, the wall surface of the main pipe 100 is sandwiched and tightened by the flange portion 11a and the pressing plate 12 ′. That is, by screwing the pressing plate 12 ′ into the cylindrical portion 11′b, any connection between the pressing plate 12 ′ and the joint main body 11 ′ and clamping of the wall surface of the main pipe 100 by the flange portion 11a and the pressing plate 12 ′ is performed. Can also be done. Accordingly, since the threaded portion formed on the inner peripheral surface of the pressing plate 12 'can be used in both the pressing plate mounting step and the pipe tightening step, a plurality of parts required for the branch pipe fitting 1 of the first embodiment. This eliminates the need to screw in the bolts, further improving work efficiency. Since the external reinforcing plate 14 'is normally manufactured in a factory, there is no influence on field work.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. .

It is a top view which shows the pipe joint for branch pipes which concerns on 1st Embodiment of this invention attached to the hole formed in the main pipe. It is AA sectional drawing of the pipe joint for branch pipes shown in FIG. It is a top view which shows the hole formed in the main pipe. It is CC sectional drawing of FIG. 3 which shows the state which inserts the collar part of a coupling main body into the hole formed in the main pipe. It is a perspective view which shows the state which inserts the collar part of a coupling main body into the hole formed in the main pipe. It is a perspective view which shows the state which inserts an internal reinforcement board in the hole formed in the main pipe. It is a figure which shows the pipe joint for branch pipes concerning 2nd Embodiment of this invention.

Explanation of symbols

1: Pipe joint 11 for branch pipe 11: Joint main body 11a: flange 12: holding plate 30: recess 50: hole 100: main pipe 101: branch pipe

Claims (9)

A pipe fitting attachment method for attaching a pipe joint for a branch pipe having a joint body having a flange and a pressing plate attached to the joint body to a circular hole formed in the pipe,
A recess forming step of forming two at a position facing the recess for partially enlarged the hole formed in the tube to one another on the circumference of the hole,
A flange insertion step of inserting the flange into the tube through the two recesses formed in the hole;
A pressing plate attaching step for penetrating the pressing plate to the joint body in which the flange portion is inserted into the pipe;
A pipe tightening step for clamping and clamping the wall surface of the pipe with the pressing plate attached to the joint main body and the flange portion inserted into the pipe. Mounting method. The concave section is characterized diameter arcuate der Rukoto than the diameter of the hole, the pipe joint fitting method according to claim 1. The joint body has a cylindrical portion;
The pressing plate has an annular shape,
Screw portions are formed on the outer peripheral surface of the cylindrical portion and the inner peripheral surface of the pressing plate,
The pressing plate attaching step is a step of attaching the pressing plate to the joint body by screwing the pressing plate into the cylindrical portion,
The tube tightening step is a step of clamping the wall surface of the tube between the flange portion and the pressing plate by further screwing the pressing plate attached to the joint main body into the cylindrical portion. The pipe joint mounting method according to claim 1 or 2, characterized in that:   The pipe joint attachment method according to any one of claims 1 to 3, wherein the branch pipe joint is attached to the pipe having a lining layer formed on an inner peripheral surface thereof. A pipe joint structure for a branch pipe attached to a circular hole formed in a pipe,
A joint body having a flange,
A holding plate attached to the joint body,
In the hole of the tube, two recesses that partially enlarge the hole are formed at positions facing each other on the circumference of the hole ,
Passing through the two recesses, inserting the flange into the pipe, clamping the wall surface of the pipe between the inserted flange and the pressing plate penetrating the joint body, A pipe joint structure for branch pipes. The recess, characterized in that than the diameter of the hole has a smaller diameter arcuate, branch pipe joint structure according to claim 5. The joint body has a cylindrical portion;
The pressing plate has an annular shape,
Screw portions are formed on the outer peripheral surface of the cylindrical portion and the inner peripheral surface of the pressing plate,
The fixing plate is attached to the joint main body by screwing the holding plate into the cylindrical portion, and the branch pipe is attached to the joint main body by screwing the branch pipe into the cylindrical portion. Item 7. The pipe joint structure for branch pipes according to Item 5 or Claim 6.   The pipe joint structure for a branch pipe according to any one of claims 5 to 7, further comprising a packing attached between the flange portion and the inner peripheral surface of the pipe.   The pipe joint structure for a branch pipe according to any one of claims 5 to 8, wherein a lining layer is formed on an inner peripheral surface of the pipe.

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